Prior art techniques relevant to first invention A will be described.
Structures for pattern formation comprising a substrate having on its surface areas different from neighboring areas in wettability, for example, by liquids have been used in various technical fields. For example, in structures for pattern formation used in printing of designs, images, letters and the like, a pattern is provided which, upon transfer of a printing ink, receives or repels the ink. In some cases, this pattern is in the form of a patterned layer or a transferred layer formed on the structure for pattern formation according to a variation in wettability.
This will described by taking printing as an example. In plates for lithography, i.e., a kind of printing method, printing ink-receptive lipophilic areas and printing ink-unreceptive areas are provided on a flat plate. In use, an ink image to be printed is formed on the lipophilic areas and then transferred and printed onto paper or the like.
In this printing, a pattern of letters, figures or the like is formed on an original plate for a printing plate to prepare a printing plate that is then mounted on a printing machine. A large number of proposals have been made on original plates for printing plates that are used in offset printing which is representative lithography.
Plates for offset printing may be produced by a method wherein the original plate for a printing plate is exposed through a mask with a pattern drawn thereon followed by development, and a method wherein the original plate for a printing plate is directly exposed by electrophotography to prepare a printing plate. The original plate for an electrophotographic offset printing plate is prepared by a method which comprises the steps of: providing a photoconductive layer composed mainly of photoconductive particles of zinc oxide or the like and a binder resin on a conductive substrate to form a photoreceptor; exposing the photoreceptor by electrophotography to form a highly lipophilic image on the surface of the photoreceptor; and subsequently treating the photoreceptor with a desensitizing liquid to hydrophilify nonimage areas to prepare an original plate for offset printing. High critical surface tension areas are immersed in water or the like and is consequently lipophobified, and a printing ink is received by the lipophilic image areas followed by transfer onto paper or the like.
An original plate for waterless lithography has also been used wherein, instead of the immersion in water to form lipophobic areas, highly lipophobic areas are formed without relying upon immersion in water or the like to form ink-receptive areas and ink-unreceptive areas.
Further, a method for producing an original plate for lithography using a heat mode recording material has been proposed which can realize the formation of highly ink-receptive areas and ink-repellent areas by laser beam irradiation. Heat mode recording materials can eliminate the need to provide the step of development and the like, and advantageously enables printing plates to be produced simply by forming an image using a laser beam. They, however, suffer from problems associated with the regulation of laser beam intensity, the disposal of residues of solid materials denatured by the laser, the plate wear and the like.
Furthermore, photolithography is known as a method for forming a high definition pattern. In this method, for example, a photoresist layer coated onto a substrate is pattern-wise exposed, and the exposed photoresist is developed, followed by etching. Alternatively, a functional material is used in a photoresist, and the photoresist is exposed to directly form a contemplated pattern.
The formation of a high definition pattern by photolithography has been used for the formation of color patterns in color filters for liquid crystal displays and the like, the formation of microlenses, the production of high definition electric circuit boards, the production of chromium masks for pattern-wise exposure and other applications. In these methods, however, in addition to the use of the photoresist, development using a liquid developing solution or etching should be carried out after the exposure. This poses problems including the necessity of treating waste liquid. Further, use of a functional material as the photoresist disadvantageously raises problems including deterioration of the photoresist by an alkaline liquid or the like used in the development.
Formation of a high definition pattern for color filters or the like by printing or the like has also been carried out. Patterns formed by printing suffer from problems of positional accuracy and the like, and, hence, in this method, it is difficult to form high definition patterns.
In order to solve these problems, the present inventors have already proposed, in Japanese Patent Application No. 214845/1997, a structure for pattern formation and a method for pattern formation wherein a material, of which the wettability is variable through photocatalytic action, is used to form a pattern. According to the present invention, in the structure and method for pattern formation using a photocatalyst, structure and method for pattern formation having better properties are provided.
It is an object of the first invention A to provide a novel structure for pattern formation and a method for pattern formation. It is another object of the first invention A to provide a novel original plate for a printing plate that can solve the problems of the conventional original plates for printing plates. It is a further object of the first invention A to provide a structure for pattern formation and a method for pattern formation that can be used to provide functional elements having excellent properties.
Prior art techniques relevant to second invention B will be described.
In liquid crystal display devices (LCDs), color filters are used in both active matrix system and simple matrix system in order to cope with an increasing demand for color display in recent years. For example, in liquid crystal displays of active matrix system using a thin film transistor (TFT), the color filter has color patterns of the three primary colors of red (R), green (G), and blue (B), and electrodes corresponding respectively to pixels of R, G, and B are turned on or off to permit a liquid crystal to function as a shutter, whereby light passes through pixels of R, G, and B to perform color display. In the case of color mixing, liquid crystal shutters corresponding to two or more pixels are opened to mix colors together so that, on the principle of additive color process, a viewer sees a different color on the retina.
Examples of methods for producing conventional color filters include a dyeing method which comprises coating a dyeing substrate onto a transparent substrate, exposing the coated substrate through a photomask, conducting development to form a pattern, and dyeing the pattern to form a colored layer, a pigment dispersion method which comprises previously dispersing a color pigment in a photosensitive resist layer provided on a transparent substrate, exposing the resist layer through a photomask, and conducting development to form a colored layer, a printing method which comprises printing colored layers using printing inks onto a transparent substrate, and an electrodeposition method which comprises forming a transparent electrode pattern on a transparent substrate and repeating, three times for R, G, and B, the energization of the transparent electrode pattern in an electrode liquid of a predetermined color to electrodeposit the color, thereby forming patterns of the colors.
In the conventional dyeing method and pigment dispersion method, however, material loss cannot be avoided in the step of coating the transparent substrate by spin coating or the like, and, further, the step of development and the step of washing are necessary for the formation of a pattern of each color. This makes it difficult to improve the efficiency of use of the material and to simplify the process and hence hinders a reduction in production cost. On the other hand, for the printing method, the formation of high definition patterns is difficult, and, for the electrodeposition method, the shape of patterns formable by the electrodepositon is limited.
In order to eliminate the above problems, a process for producing a color filter by ink-jet system has been developed. This process, however, is still unsatisfactory for solution to the problems.
The second invention B has been made under these circumstances. It is an object of the present invention to provide a color filter having high definition and free from defects such as dropouts and to provide a production process of a color filter that is excellent in efficiency of use of the material and includes neither the step of development nor the step of washing, that is, is simple in process.
Prior art techniques relevant to the third invention will be described.
Among lenses used in the art, particularly a microlens or a microlens array comprising orderly arranged microlenses has been utilized in fine optics and other fields. For example, there is an ever-increasing demand for use of the microlens or the microlens array as components constituting liquid crystal displays and as components adjacent to charge coupled solid-state image pick-up device (CCD) used in video cameras and the like.
For the production of microlenses, for example, Japanese Patent Laid-Open Nos. 21901/1991 and 164904/1993 disclose a production process which comprises forming a transparent heat deformable resin pattern by etching through a mask and heat deforming the heat deformable resin pattern to form a microlens. In this process, however, the formation of fine lenses is difficult because the direction of etching is isotropic. Further, the regulation of the focal length of the lens is limited, and the process is complicate.
Japanese Patent Laid-Open No. 165932/1990 discloses another conventional process for producing a microlens which comprises ejecting droplets of a composition for a lens onto a transparent substrate and curing the deposited droplets to form a microlens array. In this process, however, the shape of the lens is restricted by the contact angle between the transparent substrate and the composition for the lens, making it difficult to regulate the focal length. Further, in order to provide a specific contact angle, a composition for a lens having a specific surface tension should be selected. This narrows the range of selectable materials. Furthermore, the shape of the contact face is limited to a circular one, and a contact face having a polygonal pattern cannot be provided. A further problem is that enhancing the radius of curvature requires for the substrate to repel the composition for a lens. This deteriorates the adhesion.
Further, Japanese Patent Laid-Open No. 206429/1993 proposes a method wherein functions of a microlens array and a color filter array comprising a plurality of stacked color filters can be realized by a single color microlens array layer.
The color microlens array may be produced, for example, by a process described in Japanese Patent Laid-Open No. 206429/1993. This process comprises forming a color filter array by photolithography, forming microlens dies on respective color filters, and transferring the dies onto the color filter array by isotropic etching to form a microlens of the color filter array. Further, Japanese Patent Application No. 201793/1996 discloses a production process which comprises forming recesses in a lens form in a glass substrate by using a photoresist and glass etching and filing colored lens materials into respective color portions. In the former production process, however, the process is very complicate, and, in the latter production process, a lens is formed in recesses of a glass substrate, posing problems including that it is very difficult to control the step of etching and the effect of lens cannot be attained without increasing the refractive index of the lens forming material.
The third invention C solves the above problems. It is an object of the present invention to provide a process for producing a lens in a simple manner, particularly a production process that can produce fine microlenses and a microlens array with good positional accuracy and enables the focal length of microlenses to be easily altered, and lenses, microlenses, and a microlens array produced by the production process.
Prior art techniques relevant to the fourth invention D will be described.
In plates for lithography, i.e., a kind of printing method, printing ink-receptive lipophilic areas and printing ink-unreceptive areas are provided on a flat plate. In use, an ink image to be printed is formed on the lipophilic areas, and the image is then transferred and printed onto paper or the like.
In this printing, various original plates for printing plates are used. After formation of a pattern of letters, figures or the like on plates, the plates are used for printing. A large number of proposals have been made on original plates for printing plates used in offset printing, representative lithographic plates. Among them, original plates for offset printing plates directly prepared by electrophotography have been widely used in the art. The original plate for an electrophotographic offset printing plate is prepared by a method which comprises the steps of: providing a photoconductive layer composed mainly of photoconductive particles of zinc oxide or the like and a binder resin on a conductive substrate to form a photoreceptor; exposing the photoreceptor by electrophotography to form a highly lipophilic image on the surface of the photoreceptor; and subsequently treating the photoreceptor with a desensitizing liquid to hydrophilify nonimage areas to prepare an original plate for offset printing. High critical surface tension areas are immersed in water or the like and is consequently lipophobified, and a printing ink is received by the lipophilic image areas followed by transfer onto paper or the like.
An original plate for waterless lithography has also been used wherein, instead of the immersion in water to form lipophobic areas, highly lipophobic areas are formed without relying upon immersion in water or the like to form ink-receptive areas and ink-unreceptive areas.
Further, a method for producing an original plate for lithography using a heat mode recording material has been proposed which can realize the formation of highly ink-receptive areas and ink-repellent areas by laser beam irradiation.
Heat mode recording materials can eliminate the need to provide the step of development and the like, and advantageously enables an original printing plate to be produced simply by forming an image using a laser beam. They, however, suffer from problems associated with the regulation of laser beam intensity, the disposal of residues of solid materials denatured by the laser, the plate wear and the like.
In order to solve these problems, the present inventors have already proposed, in Japanese Patent Application No. 214845/1997, a structure for pattern formation and a method for pattern formation wherein a material of which the wettability is variable through photocatalytic action is used to form a pattern. In this connection, the production of press plates having excellent properties by utilizing original plates for printing plates using the pattern forming structure using a photocatalyst has been desired in the art.
It is an object of the fourth invention D to provide a press plate having excellent properties by utilizing an original plate for a printing plate using a structure for pattern formation prepared through photocatalytic action.